A clinical study to optimise a sand fly biting protocol for use in a controlled human infection model of cutaneous leishmaniasis (the FLYBITE study)

Background: Leishmaniasis is a globally important yet neglected parasitic disease transmitted by phlebotomine sand flies. With new candidate vaccines in or near the clinic, a controlled human challenge model (CHIM) using natural sand fly challenge would provide a method for early evaluation of prophylactic efficacy. Methods : We evaluated the biting frequency and adverse effects resulting from exposure of human volunteers to bites of either Phlebotomus papatasi or P. duboscqi, two natural vectors of Leishmania major. 12 healthy participants were recruited (mean age 40.2 ± 11.8 years) with no history of significant travel to regions where L. major-transmitting sand flies are prevalent. Participants were assigned to either vector by 1:1 allocation and exposed to five female sand flies for 30 minutes in a custom biting chamber. Bite frequency was recorded to confirm a bloodmeal was taken. Participant responses and safety outcomes were monitored using a visual analogue scale (VAS), clinical examination, and blood biochemistry. Focus groups were subsequently conducted to explore participant acceptability. Results: All participants had at least one successful sand fly bite with none reporting any serious adverse events, with median VAS scores of 0-1/10 out to day 21 post-sand fly bite. Corresponding assessment of sand flies confirmed that for each participant at least 1/5 sand flies had successfully taken a bloodmeal (overall mean 3.67±1.03 bites per participant). There was no significant difference between P. papatasi and P. duboscqi in the number of bites resulting from 5 sand flies applied to human participants (3.3±0.81 vs 3.00±1.27 bites per participant; p=0.56) .  In the two focus groups (n=5 per group), themes relating to positive participant-reported experiences of being bitten and the overall study, were identified. Conclusions: These results validate a protocol for achieving successful sand fly bites in humans that is safe, well-tolerated and acceptable for participants. Clinicaltrials.gov registration: NCT03999970 (27/06/2019)

Systematic functional analysis of Leishmania protein kinases identifies regulators of differentiation or survival

Differentiation between distinct stages is fundamental for the life cycle of intracellular protozoan parasites and for transmission between hosts, requiring stringent spatial and temporal regulation. Here, we apply kinome-wide gene deletion and gene tagging in Leishmania mexicana promastigotes to define protein kinases with life cycle transition roles. Whilst 162 are dispensable, 44 protein kinase genes are refractory to deletion in promastigotes and are likely core genes required for parasite replication. Phenotyping of pooled gene deletion mutants using bar-seq and projection pursuit clustering reveal functional phenotypic groups of protein kinases involved in differentiation from metacyclic promastigote to amastigote, growth and survival in macrophages and mice, colonisation of the sand fly and motility. This unbiased interrogation of protein kinase function in Leishmania allows targeted investigation of organelle-associated signalling pathways required for successful intracellular parasitism

Biodegradation of hazardous pollutants

Celem projektu było przeprowadzenie badań laboratoryjnych rozkładu biologicznego próbek gleby zanieczyszczonych PAU, PCB i NEL ze składowiska odpadów niebezpiecznych w Pozdatku. Do badań użyto czystych kultur bakteryjnych Rhodococcus sp. i Pseudomonas putida. Na podstawie wyników badań laboratoryjnych stwierdzono, że po jednym miesiącu ługowania bakteriami Rhodococcus sp. usunięto 73 % NEL, 73 % PAU i 14 % PCB. Po zastosowaniu czystej kultury Pseudomonas putida usunięto 96 % NEL, 89 % PAU i 14 % PCB.The objective of the project was a laboratory check of biodegradation of soil samples contaminated by PAU, PCB and NEL from the hazardous waste dump in the Pozd'átky locality. For the laboratory check, pure bacterial cultures of Rhodococcus sp. and Pseudomonas putida have been used. It is apparent from the laboratory experiments results that after one-month bacterial leaching, applying the bacterium of Rhodococcus sp. there is a 73 % removal of NEL, a 73 % removal of PAU and a 14 % removal of PCB. Applying a pure culture of Pseudomonas putida there is a 96 % removal of NEL, a 89 % removal of PA U and a 14 % removal of PCB

Experimental transmission of Leishmania (Mundinia) parasites by biting midges (Diptera: Ceratopogonidae)

Leishmania parasites, causative agents of leishmaniasis, are currently divided into four subgenera: Leishmania, Viannia, Sauroleishmania and Mundinia. The recently established subgenus Mundinia has a wide geographical distribution and contains five species, three of which have the potential to infect and cause disease in humans. While the other Leishmania subgenera are transmitted exclusively by phlebotomine sand flies (Diptera: Psychodidae), natural vectors of Mundinia remain uncertain. This study investigates the potential of sand flies and biting midges of the genus Culicoides (Diptera: Ceratopogonidae) to transmit Leishmania parasites of the subgenus Mundinia. Sand flies (Phlebotomus argentipes, P. duboscqi and Lutzomyia migonei) and Culicoides biting midges (Culicoides sonorensis) were exposed to five Mundinia species through a chicken skin membrane and dissected at specific time intervals, post bloodmeal. Potentially infected insects were also allowed to feed on ear pinnae of anaesthetized BALB/c mice and the presence of Leishmania DNA was subsequently confirmed in the mice using polymerase chain reaction analyses. In C. sonorensis, all Mundinia species tested were able to establish infection at a high rate, successfully colonize the stomodeal valve and produce a higher proportion of metacyclic forms than in sand flies. Subsequently, three parasite species, L. martiniquensis, L. orientalis and L. sp. from Ghana, were transmitted to the host mouse ear by C. sonorensis bite. In contrast, transmission experiments entirely failed with P. argentipes, although colonisation of the stomodeal valve was observed for L. orientalis and L. martiniquensis and metacyclic forms of L. orientalis were recorded. This laboratory-based transmission of Mundinia species highlights that Culicoides are potential vectors of members of this ancestral subgenus of Leishmania and we suggest further studies in endemic areas to confirm their role in the lifecycles of neglected pathogens. Copyright: © 2021 Becvar et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited

How to do a good systematic review of effects in international development: a tool kit

We provide a ‘how to’ guide to undertake systematic reviews of effects in international development, by which we mean, synthesis of literature relating to the effectiveness of particular development interventions. Our remit includes determining the review's questions and scope, literature search, critical appraisal, methods of synthesis including meta-analysis, and assessing the extent to which generalisable conclusions can be drawn using a theory-based approach. Our work draws on the experiences of the International Initiative for Impact Evaluation's (3ie's) systematic reviews programm